livro spectrochemical analysis

8/12/2019 Livro Spectrochemical Analysis

1/9

Spectrochemical

Analysis

JAMES D. INGLE JR.

Oregon State University

STANLEY R. CROUCH

Michigan State University

Prentice Hall, Englewood Cliffs,

ew

Jersey 07632


2/9

Contents

PREFACE

XII I

SPECTROCHEMICAL INFORMATION

1-1 Ra diatio n/M atter Intera ction s, 1

1-2 Na tur e of Spe ctroch em ical

Analysis, 2

Types of analyses, 3

Samples, 3

Spectrochemicalphenomena,4

Analysis ofreal samples, 5

1-3 Ex pres sion s of An alytic al

Information, 6

alibration data, 6

Atomic andmolecular

spectra,

7

Optimization ofthe responsefunction, 8

1-4 Ev aluation Criteria in Spectrochem ical

Techniques, 9

Practica considerations, 9

Automation and multiplespecies capability, 9

Interferences an dselectivity, 9

Figures ofmerit 10

Overview, 11

Problems, 11

References, 11

SPECTROCHEMICAL MEA SUREM ENTS 1 3

2-1 Com plete Spect rochemical M easure men t , 13

2-2 Exp ressio ns of Op tical Inte nsity , 15

Radiometrie System, 15

Photometrie System, 18

2-3 Spectroche mical M eth ods , 18

Emission

spectroscopy,

18

2-4

Absorption spectroscopy, 20

Luminescence spectroscopy, 21

Scatteringmethods, 21

Selection of Optical Information, 22

Wavelength selection, 22

Other

selection criteria,

23

v


3/9

VI

ontents

2 -5 M e a s u r e m e n t o f O p t i c a l S i g n a l s , 2 3

Analytical signal, 24

Emission and chemiluminescence spectrometry, 24

Photoluminescence spectrometry, 25

Absorption spectrometry, 25

P r o b l e m s , 2 7

R e f e r e n c e s , 2 8

OPTICAL CO MPO NEN TS OF SPECTROMETERS 30

3 -1 B a s i c O p t i c a l R e l a t i o n s h i p s , 3 0

The conservation law, 30

The laws of reflection and refraction, 31

The absorption law, 34

3 -2 In t e r f e r e n c e , D i f f r a c t i o n , a n d P o l a r i z a t i o n o f

E l e c t r o m a g n e t i c W a v e s , 3 5

Superposition of waves, 35

Interference, 37

Diffraction, 37

Polarization of light, 39

3 -3 M o d u l a t o r s , 4 4

Mechanical choppers, 45

Electro-optic and magneto-optic modulators, 45

Acousto-optic modulators, 45

3 -4 Im a g i n g a n d B e a m D i r e c t i n g O p t i c s , 4 7

Mirrors, 48

Lenses, 51

Image irradiance, 53

Optical aberrations, 55

Beam Splitters, 56

Fiber optics, 59

3 -5 F i l t e r s , P r i s m s , a n d G r t i n g s , 6 0

Filters, 60

Prisms, 63

Diffraction gratings, 64

3 -6 D i s p e r s i v e W a v e l e n g t h S e l e c t i o n S y s t e m s , 6 7

Monochromators, 67

Polychromators and spectrographs, 76

3 -7 N o n d i s p e r s i v e S y s t e m s , 7 8

Fabry-Perot interferometer, 78

Michelson interferometer, 81

Other interferometers, 83

Advantages of Fourier transform m ethods, 84

P r o b l e m s , 8 4

R e f e r e n c e s , 8 6

OPTICAL SOURCES TRANSDUCERS AND MEAS UREM ENT SYSTEM S 8 7

4 - 1 B l a c k b o d y R a d i a t i o n , 8 7

Planck's law, 88

Approximate blackbody expressions, 89

Einstein coefficients, 89

Applications to spectroscopy, 90

4 -2 C o n v e n t i o n a l R a d i a t i o n S o u r c e s , 9 1

Characteristics of sources, 91

Continuum sources, 92

Continuum plus line sources, 95

Line sources, 95

Miscellaneous sources, 97

Standard sources, 97

4 - 3 La s e r S o u r c e s , 9 8

Principles of lasers, 98

Laser types, 99

Laser characteristics, 105

Nonlinear optical effects, 105

Summary, 106

4 -4 O p t i c a l T r a n s d u c e r s , 1 06

Transducer characteristics, 107

4-5

4-6

Thermal detectors, 108

Photon detectors, 109

Mulchannel detectors, 114

S i g n a l P r o c e s s i n g a n d R e a d o u t S y s t e m s , 1 1 7

General considerations, 1 18

Modulation principles, 119

Signal conditioning, 121

Analog signal processing, 123

Compu ter data acquisition, 127

Digital signal processing, 127

Readout and display Systems, 128

O p t i c a l S p e c t r o m e t e r s , 1 28

Single-channel spectrometers, 128

Mulchannel spectrometers, 129

Multiplexing Systems, 131

Quantitative readout expressions, 131

P ro b l e m s , 1 3 2

R e f e r e n c e s , 1 3 3


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ontents vii

SIGNAL-TO-IMOISE RATIO CO NSIDE RAT IONS 13 5

5-1 Ch ara c te r i s t i c s o f S igna l s an d No ise , 135

Noise magnitude, 136

Noise types, 136

Signal characteristics and the signal-to-noise ratio,

137

5 -2 F r e q u e n c y C h a ra c t e r i s t i c s o f S i g n a l P ro c e s s i n g

a n d R e a d o u t S y s t e m s , 1 3 8

Amplitude transfer function, 138

System bandpass, 139

Noise in readout Signals, 140

5-3 No ise So urc es , 141

Quantum , secondary em ission, and shot noise, 141

Flicker noise, 144

Other noise sources, 145

5 -4 S i g n a l - t o -N o i s e Ex p re s s i o n s fo r Em i s s i o n a n d

L u m i n e s c e n c e M e a s u r e m e n t s , 1 4 6

General expressions, 146

Blank-noise-limited SIN expressions, 148

Signal-shot-noise-limited expressions, 149

Signal-flicker-noise-limited expressions, 149

Dependence of SIN on analytical Signal, 149

5-5

5-6

S i g n a l - t o -N o i s e E x p r e s s i o n s fo r A b s o r p t i o n

M e a s u r e m e n t s , 1 5 0

General equations, 150

0% T noise-limited expressions, 152

Signal-shot-noise-limited expressions, 153

Signal-flicker-noise-limited expressions, 153

Other noise sources, 153

Direct absorbance readout, 153

S i g n a l - t o - N o i s e E n h a n c e m e n t T e c h n i q u e s , 1 5 4

Frequency-domain filtering, 154

Adjustment of analytical and background signal

levels, 155

Photon counting, 155

Modulation techniques, 156

Double-beam and dual-channel techniques, 158

Time-domain filtering, 159

Multichannel and multiplex Systems, 160

P r o b l e m s , 1 6 1

R e f e r e n c e s , 1 6 2

METHODOLOGY IN SPECTROCHEMICAL ANALYSIS 1 6 4

6 -1 Ex t e r n a l S t a n d a rd C a l i b r a t i o n , 1 6 4

6 -2 S y s t e m a t i c E r ro r s i n S p e c t ro c h e m i c a l

M e t h o d s , 1 6 5

Matrix errors, 165

Calibration errors, 167

Sample acquisition, preparation, and measurement

errors, 168

6 -3 R a n d o m E r r o r s i n S p e c t r o c h e m i c a l

M e a s u r e m e n t s , 1 6 8

Determination of Standard deviation in

concentration, 168

Statistical Statements, 169

Other considerations, 170

6 -4 S e n s i t i v it y a n d D e t e c t i o n L i m i t , 1 7 1

Sensitivity, 171

Detection limit, 172

6 -5 Te c h n i q u e s fo r M i n i m i z a t i o n o f S y s t e m a t i c a n d

R a n d o m E r r o r s , 1 7 6

Separations, 176

Saturation, buffer, and masking methods, 176

Dilution, matrix match, and parametric methods, 177

Internal blank and Standard methods, 177

Method of Standard additions, 17 8

Methods based on optical encoding, 180

Chemical selectivity, 181

Instrumental correction methods, 182

6 -6 A u t o m a t e d S p e c t r o c h e m i c a l M e a s u r e m e n t s ,

183

P r o b l e m s , 1 8 6

R e f e r e n c e s , 1 8 8

7

INTRODUCTION TO ATOMIC SPECTROSCOPY 1 8 9

7 -1 S a m p l e I n t r o d u c t i o n a n d A t o m i z a t i o n , 1 89

Overview, 190

Nebulizers, 192

Free-atom formation fter nebulization, 195

Free-atom formation with discrete sample

introduction, 198

7 -2 In t e r f e r e n c e s i n A t o m i c S p e c t ro s c o p y , 1 9 8

Blank interferences, 198

Analyte interferences, 199

7 - 3 E l e c t ro n i c S t a t e s o f A t o m s , 2 0 2

Quantum numbers, 202

Coupling schemes, 203

Term Symbols, 203

Selection rules and atomic spectra, 205

Additional Splitting effects, 207

Statistical weights and partition functions, 207

7-4 Spe c t ra l Li ne Pro f i l es , 209

Lifetime broadening, 209


5/9

ontents

7 5

Doppler broadening, 211

Other causes of line broadening, 212

Overall line profiles, 213

S p e c t r a l L i n e In t e n s i t i e s , 2 1 4

Thermal emission, 214

8

Absorption, 217

Atomic fluorescence, 219

P r o b l e m s , 2 2 2

R e f e r e n c e s , 2 2 3

FLAME AND PLASMA ATOMIC EMISSION SPECTROMETRY 2 2 5

T h e I d e a l A t o m i c E m i s s i o n S p e c t r o m e t r i c

Sys tem, 226

Information desired from emission spectra, 226

Characteristics of the ideal emission source, 226

Atomizer temperature, 227

F l a m e A t o m i c Em i s s i o n S o u rc e s , 2 2 7

Properties of flames, 228

Sample introduction into flames, 231

Atomization and excitation characteristics, 232

Compa rison to the ideal source, 23 3

P l a s m a A t o m i c Em i s s i o n S o u rc e s , 2 3 3

Inductively coupled plasmas, 233

Microwave plasmas, 237

DC plasmas, 238

F l a m e a n d P l a s m a E m i s s i o n S p e c t r o m e t e r s ,

239

Wavelength selection, 239

Transducers and electronic components, 243

Computer control, 244

8 -5 S i g n a l a n d N o i s e C o n s i d e r a t i o n s , 2 4 4

Readout Signals, 244

Signal-to-noise expressions, 245

Signal-to-noise optimization, 246

8 -6 P e r fo rm a n c e C h a ra c t e r i s t i c s , 2 4 7

Linearity, 247

Precision, 248

Accuracy, 249

Detection limits, 251

8 -7 M e t h o d o l o g y a n d A p p l i c a t i o n s , 2 5 1

Identification and selection of analytical lines, 252

Analytical procedures, 253

Applications, 253

P r o b l e m s , 2 5 5

R e f e r e n c e s , 2 5 6

ARC AND SPARK EM ISSIO N SPECTROMETRY 25 7

9 -1 A re Ex c i t a t i o n S o u rc e s , 2 5 8

Free-burning de arcs, 258

Other types of arcs, 260

Arcs as ideal emission sources, 261

9 -2 H i g h -V o l t a g e S p a rk s a n d O t h e r Em i s s i o n

S o u rc e s , 2 6 2

The high-voltage spark discharge, 262

Miscellaneous excitation sources, 265

9 -3 I n s t r u m e n t a t i o n a n d P e r f o r m a n c e

C h a ra c t e r i s t i c s , 2 6 7

Photographic detection for arc and spark emission,

267

Performance characteristics, 268

9 -4 M e t h o d o l o g y a n d A p p l i c a t i o n s , 2 6 9

Qualitative and semiquantitative methods, 269

Quantitative methods, 270

Applications, 270

P r o b l e m s , 2 7 1

R e f e r e n c e s , 2 7 1

10 ATOM IC ABSORPTION SPECTROPHOTOMETRY 27 3

1 0 - 1 A t o m i z e r s , 2 7 4

Flame atomizers, 274

Electrothermal atomizers, 275

Other sample introduction and atomization

techniques, 278

10-2 S igna l and No ise Ex pre ss io ns , 280

Readout expressions, 280


1 0 - 3 In s t ru m e n t a t i o n , 2 8 7

Comm on features of commercial AA

spectrophotometers, 287

Double-beam Systems, 288

Background correction, 288

Multielement spectrophotometers, 294

1 0 -4 P e r fo r m a n c e C h a ra c t e r i s t i c s , 2 9 6

Linearity, 296

Precision, 298

Accuracy, 298

Characteristic concentrations and detection limits,

299

1 0 -5 M e t h o d o l o g y a n d A p p l i c a t i o n s , 3 0 1

Flame atomization, 301

Electrothermal atomization, 302

Applications, 303

P r o b l e m s , 3 0 4

R e f e r e n c e s , 3 0 5


6/9

ontents

IX

11

ATOMIC FLUORESCENCE SPECTROMETRY 3 7

1 1-1 T y p e s o f F l u o re s c e n c e , 3 0 7

1 1-2 I n s t ru m e n t a t i o n , 3 0 9

Excitation sources, 310

Atomizers and sample introduction, 311

Wavelength selection a nd Signal processing, 312

Multielement Instrumentation, 312

1 1- 3 S i g n a l a n d N o i s e Ex p re s s i o n s , 3 1 3

Signal expressions, 313

Saturated fluorescence, 316


1 1 - 4 P e r f o r m a n c e C h a r a c t e r i s t i c s

a n d A p p l i c a t i o n s , 3 2 0

Linearity, 320

Precision and accuracy, 320


Applications, 321

Overview, 322

P r o b l e m s , 3 2 3

R e f e r e n c e s , 3 2 4

12 INTRODU CTION TO MOLECULAR SPECTROSCOPY 32 5

1 2 -1 M o l e c u l a r S p e c t r a , 3 2 6

1 2-2 R o t a t i o n a l S p e c t r a , 3 2 6

1 2-3 V i b r a t i o n a l S p e c t r a , 32 7

Pure vibrational transitions, 327

Rotation-vibrational transitions, 328

1 2-4 E l e c t ro n i c A b s o rp t i o n S p e c t r a o f D i a t o m i c

Mo l e c u l e s , 3 2 9

Electronic states, 329

Electronic transitions, 331

1 2-5 E l e c t ro n i c A b s o rp t i o n S p e c t r a o f P o l y a t o m i c

Mo l e c u l e s , 3 3 4

Electronic states and transitions, 335

Electronic spectra, 336

Electronic band shapes and intensities, 337

1 2 -6 L u m i n e s c e n c e S p e c t r a , 3 3 8

Processes of deactivation, 338

Quantum efficiencies and power yields, 339

Luminescence lifetimes, 342

Quenching and excitedstate reactions, 343

Band shapes, 344

Structural effects, 344

Environmental effects, 347

Polarization of luminescence, 348

P r o b l e m s , 3 4 9

R e f e r e n c e s , 3 5 0

13

ULTRAVIOLET AN D VISIBLE MOLECULAR ABSO RPTION SPECTROPH OTOM ETRY 35 2

1 3 -1 I n s t ru m e n t a t i o n , 3 5 2

Instrumental components, 354

Readout considerations, 361

Other features, 363

13-2 S igna l and No ise Express ions , 365

Readout expressions, 365


1 3-3 A p p a re n t D e v i a t i o n s f ro m B e e r s La w , 3 7 2

Nonzero intercept, 372

Nonlinearity due to chemical equilibria, 373

Nonlinearity due to other chemical effects, 373

Nonlinearity du e to polychromatic radiation, 373

Nonlinearity due to stray radiation, 37 6

Other instrumental causes of nonlinearity, 379

13-4 M e t h o d o l o g y a n d P e r f o r m a n c e C h a r a c t e r i s t i c s ,

381

General considerations in quantitative analysis, 381


1 3 -5 A p p l i c a t i o n s , 3 8 6

Qualitative analysis, 386

Fundamental applications, 386

Conventional quantitative determinations, 387

Determination of inorganic species, 387

Multicomponent determinations, 390

Spectrophotometric titrations, 390

Reaction-rate methods of determination, 391

Other quantitative techniques and uses, 394

Chromatographie applications, 396

Automated measurements, 398

Reflectance measurements, 398

Optical rotatory dispersion and circular dichroism

measurements, 398

P r o b l e m s , 3 9 9

R e f e r e n c e s , 4 0 2


7/9

x ontents

14

INFRAREO SPECTROMETRY 40 4

14-1 Basis of Infrared Absorption, 405

Requirements for infrared absorption, 405

Number of vibrational modes, 405

Group frequencies, 407

Vibrationalcoupling 408

14-2 Ins trumentat ion 408

Dispersive IR spectrophotometers, 408

Fourier transform IR spectrometers, 412

Nondispersive IR instruments, 415

14-3 S a m p l e P r e p a r a t i o n Te c h n i q u e s 4 1 7

Gas samples, 417

Liquid samples, 417

Solid samples, 419

Microsampling devices, 419

14-4 Qua l i tat ive Ana lys i s and Structure

D e t e r m i n a t i o n 4 2 0

Correlation Charts, 421

Spectral collections and search Systems, 422

Applications, 422

14-5 Quantitative Infrared Absorption

Spectrophotometry, 423

Nonlinearities, 423

Measuremen t of absorption, 424

Precision of IR absorption measurem ents, 425

Applications, 426

14-6 Near-Infrared and Far-Infrared

Absorption, 427

Near-infrared spectrometry, 427

Far-infrared spectrometry, 428

1 4 -7 I n f r a r e d R e f l e c t i o n a n d E m i s s i o n , 4 2 9

Infrared reflectance methods, 429

Infrared emission spectroscopy, 434

Problems, 435

References, 436

15

MOLECULAR LUMINESCENC E SPECTROMETRY 4 3 8

15-1 Instrumentation, 439

Excitation sources, 440

Wavelength-selection devices, 441

Sample compartment and sample cells, 442

Cell geometry, 443

Detectors, 443

Data processing, m anipulation, and readout 443

Data presentation, 444

Compensation and correction techniques, 446

15-2 Signal and Noise Ex pression s, 449

Signal expressions, 450

Refinements of Signal expressions, 455

Solution variables, 456

Corrected measurements, 457

Saturation effects, 458



15-3 Molecular Fluorescence Spectrom etry, 461

Methodology, 462

Background Signals, 462


Qualitative analysis, 466

Fundamental applications, 466

Quantum efficiency determinations, 466

Quantitative analysis, 467

Multicomponent analysis, 470

Spectrofluorometric titrations, 471

Fluorescence Chromatographie detection, 471

Vapor-phase fluorescence, 47 2

Immunoassays, 472

Remote sensing 472

1 5- 4 M o l e c u l a r P h o s p h o r e s c e n c e S p e c t r o m e t r y , 4 73

Low-temperature phosphorescence, 473

Room-temperature phosphorescence, 474

Instrumentation, 477

Methodology, 478


Applications, 478

1 5- 5 C h e m i l u m i n e s c e n c e , 4 7 8

Principles, 479


Solution chemiluminescence, 482

Bioluminescence, 484

Gas-phase chemiluminescence, 484

Electrochemiluminescence, 484

15-6 Lifetime and Polarization M easurem ents, 485

Lifetime measurements, 485

Polarization techniques, 489

Problems, 490

References, 491


8/9

ontents x i

16

MOLECULAR SCATTERING METH ODS 49 4

16-1

16-2

16-3

P r i n c i p l e s o f R a d i a t i o n S c a t t e r i n g , 4 9 4

Elastic scattering, 495

Inelastic scattering, 497

R a m a n S p e c t r o s c o p y , 4 9 9

Theory, 500


Compa rison of Raman and IR spectrometry, 507

Resonance Raman spectrometry, 508

Applications, 509

Nonlinear Raman scattering, 511

T u r b i d i m e t r y a n d N e p h e l o m e t r y , 5 1 3

Instrumentation and theory, 513

Applications, 515

1 6 -4 La s e r S c a t t e r i n g M e t h o d s , 5 1 5

Molecular weight determinations, 515

Low-angle scattering, 518

Quasi-elastic light scattering, 519

Brillouin scattering, 520

1 6 -5 R e m o t e S e n s i n g w i t h La s e r s , 5 2 2

Laser radar, 522

Applications, 522

P r o b l e m s , 5 2 3

R e f e r e n c e s , 5 2 4

17

SPECTROC HEMICAL TECHN IQUES ON THE HORIZON 52 5

1 7-1 P h o t o a c o u s t i c S p e c t ro m e t ry , 52 5


Principles, 527

Applications, 528

1 7-2 Th e r m a l Le n s i n g S p e c t ro m e t r y , 5 2 9


Models of thermal lens formation, 530

Analytical applications, 531

Related thermo-optical methods, 532

1 7 -3 L a s e r I o n i z a t i o n of A t o m s , 5 3 2

Laser-enhanced ionization methods, 533

Resonance ionization methods, 535

Summary, 536

1 7- 4 M i s c e l l a n e o u s L a s e r - B a s e d T e c h n i q u e s , 5 36

Intracavity absorption, 536

Molecular multiphoton ionization, 537

Doppler-free absorption spectroscopy, 538

R e f e r e n c e s , 5 4 1

A

STATISTICAL CONCEPTS 54 3

A - l S t a t i s ti c a l Q u a n t i t i e s , 5 4 3

Mean and Standard deviation, 543

Probability distributions, 543

Hypothesis testing, 547

Confidence intervals, 547

A -2 P ro p a g a t i o n o f U n c e r t a i n t i e s , 5 4 8

R e f e r e n c e s , 5 4 9

B

PROPERTIES OF OPTICAL MATERIALS 55 0

B-l Refr ac t ive Ind ice s , 550

B -2 T r a n s m i s s i o n C h a ra c t e r i s t i c s , 5 5 1

B -3 R e f l e c t a n c e o f M i r ro r M a t e r i a l s , 5 5 1

B -4 O t h e r P ro p e r t i e s , 5 5 2

R e f e r e n c e s , 5 5 3


9/9

xii

ontents

C CHARACTERISTICS OF OPTICAL FILTERS 55 4

References, 556

D PHOTOM ULTIPLIER TUBE SPECIFICATIONS 55 7

E SAMPLE PREPARATION METHO DS 5 6 0

E-l Sample Dissolution M ethod s, 560

E-2 Separation and Preco ncen tration, 561

References, 561

F ATOMIC AND MOLECULAR TRAN SITIONS 56 3

F-l Einstein Coefficients, 564

F-2 Oscillator Stren gths, 564

F-3 Relationships between Expe rimental and

Fundamental Quantities, 565

F-4 Unit Con siderations, 567

UNITS CONSTAN TS CONVERSION FACTORS ABBREVIATIONS

A N D Q U A N T U M N U M B E R S 5 6 8

S Y M B O L S 5 7 1

INDEX 5 7 7

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